The invention hereinafter described concerns an electronic timepiece provided with a circuit directed to time setting and correction. The operating principles of quartz-standard timepieces have now become relatively well known. Generally, a quartz resonator is followed by a frequency divider and this in turn serves to control the operation of either a miniature stepping motor which drives the time indicating hands or alternatively the output of the frequency divider may be applied via a decoder to form numerals on a time indicating surface, such numerals being of either a passive or an active nature. The present invention is more particularly directed to a timepiece of the former variety which is to say the display is formed by time indicating hands moved by a miniature stepping motor.
In most of the quartz timepieces placed on the market up to the present time one of the principal disadvantages resides in the bulk of the instruments. This bulk discourages the development of elegant watch casings and hinders serious use of such timepieces as jewelry. It has, therefore, become desirable to find ways and means of reducing this bulk. Some portions of the internal mechanism and components are only with difficulty reducible, for example a power cell tends to take a comparatively large proportion of the available space. Other components of such timepieces have included the various mechanisms associated with setting the hands and for correcting such setting. Such mechanisms tend to be similar to those associated with classical types of mechanical watches and therefore complex and bulky.
One proposition which provides an improvement to these particular drawbacks is to be found in British Pat. No. 1,405,677. Herein there was suggested that the correcting functions be somewhat simplified by avoiding the use of a seconds hand, driving the minutes hand directly from the stepping motor and arranging for electronic correction of the setting of the minutes hand. A mechanical correction was provided for setting the hours hand or changing the date and thus certain complexities continue to be present. A suitable circuit usable in respect of the arrangement of U.S. Pat. No. 1,405,677 may be found for example in U.S. Pat. No. 1,434,443.
A further advantage drawn from the arrangements found in U.S. Pat. No. 1,405,677 lay in the suggestion that in view of the direct driving of the minutes hand by the stepping motor the stepping could be carried out less frequently than where a seconds hand was employed and this less frequent stepping would lead to a lessening of the power consumption and thereby make possible a smaller battery. The timepiece thus described in these prior patent specifications is now successfully incorporated in commercially available products and in particular has found use in a lady's wrist watch.
Recently, it has become clear that still further improvements in this direction were both possible and desirable. To this effect British Pat. No. 28844/76 describes an arrangement in which there is no seconds hand and no date display. While this may seem to be a strictly negative improvement, nevertheless, it has been found that a very considerable diminution of the overall size is possible, particularly in view of the fact that as described in the above-mentioned application there are no mechanical correcting arrangements whatsoever and all time setting and correcting arrangements are carried out electronically. The correction arrangement insofar as the user is concerned is particularly simple and comprises nothing more than a single pushbutton arranged, for example, to correspond with the normal position of the crown of a mechanical wristwatch. The watch as described in our co-pending application mentioned hereinabove is provided with a stepping motor which is utilized to drive directly the minutes and hour hands through a system of planetary gears. The arrangement is such that the minutes hand is stepped once per minute and this further conserves power as already taught in our prior U.S. Pat. No. 1,405,677 thereby enabling the use of a much smaller battery.
A circuit suitable for providing the necessary time setting and correcting functions is set forth hereinafter. In particular the following features should be available in such a watch:
(a) It should be possible to obtain minutes hand setting.
(b) It should be possible to set the phase of the seconds even though the seconds themselves are not displayed, that is to say that when a time signal is received the minute hand should be just at the point of changing over.
(c) It should be possible to change rapidly the hour hand setting as in the case when the user is travelling between time zones or when there is a change between winter and summer time as is the case in many countries.